Conventional curvature sensors sense curvature variation of a sample, and each curvature sensor is mainly divided into a mechanical sensor and an optical sensor.
The mechanical sensor senses curvature variation of the sample by sensing tension or compression. The optical sensor senses curvature variation of the sample by using a light source.
U.S. Patent No. US 20080192261 discloses an apparatus and a method for examining a curved surface. The apparatus has a camera and a lamp. The camera can be aimed at the inside of the curved surface. The lamp can be located such that light emitted by the lamp is reflected from the inside of the curved surface into the camera.
However, the foregoing apparatus and method need an electrical source or a light source, which dissipate energy and cannot sense curvature variation of a sample remotely.
Accordingly, a new, non-energy dissipating, curvature sensing device and method are needed to overcome the foregoing problems.